Which case ruled that students retain their First Amendment rights while in school?

The case that established that students retain their First Amendment rights while in school is Tinker v. Des Moines. In this landmark decision, the Supreme Court recognized that the rights of students do not end at the schoolhouse gates, affirming the principle that students are entitled to express their opinions and engage in symbolic speech, as long as it does not disrupt the educational environment. The case involved students who wore black armbands to protest the Vietnam War, and the Court ruled that their free speech rights were protected, emphasizing the importance of constitutional rights in educational settings.

In contrast, the other cases mentioned focus on different issues. Plessy v. Ferguson dealt with racial segregation and established the "separate but equal" doctrine. Brown v. Board of Education later overturned Plessy by ruling that segregated schools were unconstitutional. Citizens United v. Federal Election Commission involved campaign finance and the regulation of political spending, rather than student rights. Each of these cases plays a significant role in U.S. legal history, but Tinker v. Des Moines specifically addresses the First Amendment rights of students in a school context.